Which of the following finding is associated with alkaptonuria?

Ans. is 'a' i.e., Ochronosis Alkaptonuria (black urine disease, black bone disease, or alcaptonuria)o It is a rare autosomal recessive disorder which is an inborn error of metabolism. It is caused by a mutation in the HGD gene for the enzyme homogentisate 1,2-dioxygenase. The gene defect makes the body unable to properly break down certain amino acids (tyrosine and phenylalanine). As a result, a substance called homogentisic acid builds up in the skin and other body tissues and its oxidated form alkapton are excreted in the urine, giving it an unusually dark color.o The accumulating homogentisic acid causes damage to cartilage (ochronosis, leading to osteoarthritis) and heart valves as well as precipitating as kidney stones and stones in other organs. Symptoms usually develop in people over thirty years old, although the dark discoloration of the urine is present from birth